1. Field of the Invention
The present invention relates to a method for manufacturing an electron source comprising a large number of electron-emitting devices arranged and a method for manufacturing a display apparatus including the electron source.
2. Related Background Art
The electron-emitting devices include a field emission electron-emitting device, a metal/insulator/metal electron-emitting device and a surface conduction electron-emitting device. An arrangement, manufacturing method and the like of the surface conduction electron-emitting device are disclosed in Japanese Patent Application Laid-Open No. 7-235255 and Japanese Patent No. 2903295, for example.
Now, the surface conduction electron-emitting device disclosed in the specifications will be outlined in brief.
As schematically shown in FIG. 14, the surface conduction electron-emitting device comprises a substrate 1, a pair of device electrodes 2, 3 facing each other on the substrate 1, and an electroconductive film 144 including an electron-emitting region 145 and connected to the device electrodes.
The electron-emitting region 145 is formed in the following manner. First, the electroconductive film 144 is placed to interconnect the electrodes 2 and 3, and then, a process step referred to as a xe2x80x9cformingxe2x80x9d is carried out. In this step, a voltage is applied across the electrodes 2 and 3 in a high vacuum to pass a current through the electroconductive film 144, thereby forming a gap in the part of electroconductive film 144. Then, a process step referred to as an xe2x80x9cactivationxe2x80x9d is carried out. In this step, a deposit 146 mainly composed of carbon and/or carbon compound is provided in the gap formed by the xe2x80x9cformingxe2x80x9d and on the electroconductive film in the vicinity of the gap.
In this way, carrying out the xe2x80x9cformingxe2x80x9d and the xe2x80x9cactivationxe2x80x9d provides the electron-emitting region 145. Here, the deposit 146 comprises two parts facing each other with a gap in-between, the gap being narrower than the gap formed in the electroconductive film 144. In the activation step, a pulsed voltage is applied to the device in an atmosphere containing an organic material. Then, as the deposit 146 mainly composed of carbon and/or carbon compound accumulates, a current passing through the device (device current If) and a current emitted to the vacuum (emission current Ie) are substantially increased, whereby better electron-emitting property can be provided.
Besides, in Japanese Patent Application Laid-Open No. 9-237571, there is disclosed a method for manufacturing an electron-emitting device, the method including, instead of the xe2x80x9cactivationxe2x80x9d step, a step of applying an organic material, such as a thermosetting resin, an electron beam polymerization type negative resist and polyacrylonitrile, on the electroconductive film and a step of carbonizing the same.
Then, combining the electron source comprising a plurality of such electron-emitting devices with a light-emitting member such as a phosphor or the like can provide an image-forming apparatus, such as a flat panel display.
As for the electron source comprising a plurality of electron-emitting devices and the image display apparatus, it has been demanded that the manufacturing methods therefor are simple, and an image can be displayed on a large screen for a long time with high definition, brightness and uniformity.
Thus, for the electron source or image display apparatus involving the surface conduction electron-emitting devices, it is desired to provide a further simplified manufacturing process as well as a further enhanced uniformity in electron-emitting property between the devices.
Therefore, an object of this invention is to provide simple methods for manufacturing an electron source with excellent and highly uniform electron-emitting property and an image display apparatus including the electron source.
To attain the object, this invention has been devised as follows.
Specifically, according to this invention, there is provided a method for manufacturing an electron source, comprising:
(A) a step of disposing a plurality of units and a plurality of wirings connected to the plurality of units on a substrate, each unit comprising a polymer film (an organic polymer film) and a pair of electrodes with the polymer film interposed therebetween; and
(B) a step of forming electron-emitting devices from the plurality of units by sequentially repeating a process including a selecting substep of selecting a desired number of units from the plurality of units, a resistance-reducing substep of reducing resistance of the polymer films of the selected units and a gap-forming substep of forming a gap in each of the films obtained by the resistance-reducing substep.
Preferably, in the method for manufacturing an electron source according to this invention, the number of the units selected at one time is two or more.
Preferably, the gap is formed by passing a current through the film obtained by the resistance-reducing substep.
Preferably, the plurality of wirings comprises a plurality of row-directional wirings and a plurality of column-directional wirings crossing the row-directional wirings with an insulating layer interposed therebetween, and each of the plurality of units is connected to one of the plurality of row-directional wirings and one of the plurality of column-directional wirings.
Preferably, the selected units are a plurality of units connected to a same row-directional wiring or same column-directional wiring.
Preferably, the resistance of the polymer film is reduced by irradiating the polymer film with an energy beam.
Preferably, the energy beam is emitted from a plurality of energy beam irradiation source.
Preferably, the energy beam is an electron beam.
Preferably, the energy beam is a light beam.
Preferably, the energy beam is a laser beam.
Preferably, the energy beam is an ion beam.
Furthermore, according to this invention, there is provided a method for manufacturing a display apparatus having an electron source comprising a plurality of electron-emitting devices and a light emitting member that emits light in response to being irradiated with an electron emitted from the electron source, in which the electron source is manufactured by the method for manufacturing an electron source according to this invention described above.
According to this invention, a large number of polymer films (organic polymer films) can be reduced in resistance (conductivity can be imparted thereto), and a gap can be formed in each of a large number of the films obtained by reducing resistance of the large number of polymer films. That is, a large number of polymer films (organic polymer films) are formed, some (typically one) polymer film(s) selected among therefrom is/are transformed (reduced in resistance) to impart a sufficient conductivity thereto, and a current is applied to the transformed film(s) to form a gap in each film. Then, other (another) polymer film(s) is/are transformed to impart a sufficient conductivity thereto, and a current is applied to the transformed film(s) to form a gap in each film. Such a process is sequentially repeated. Thus, the gaps can be formed on all the transformed films eventually.
One effective method for reducing the resistance of some or one polymer film(s) is to transform the polymer film(s) by irradiating the polymer film(s) with an electron beam, light beam or ion beam. Using the electron beam, light beam or ion beam enables the resistance of only the selected polymer film(s) to be reduced in a relatively short time, and therefore, the power required for the xe2x80x9cformingxe2x80x9d can be distributed in terms of time. Thus, enhancement in screen size and production scale can be readily realized, and the electron-emitting devices with uniform property can be arranged over the whole display region.
With the manufacturing method according to this invention, an electron source with high efficiency capable of maintaining a highly uniform electron-emitting property for a long time can be manufactured. Thus, with the manufacturing method according to this invention, an image display apparatus capable of displaying a stable image with high brightness and uniformity for a long time can be manufactured.